• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.124-131
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• 2002

In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect talc calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments. for 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. And a generalized volumetric error model formulator for three-axis machine tools was developed, which allowed us to formulate machine tool synthesis error models far all possible machine tool configurations only with machine tool topology information. Based on these volumetric error model and model formulator, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.90-99
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• 1999

A vehicle driving simulator is a virtual reality device which a human being feels as if the one drives a vehicle actually. The driving simulator is used effectively for studying interaction of a driver-vehicle and developing vehicle system of a new concept. The driving simulator consists of a vehicle motion bed system, motion controller, visual and audio system, vehicle dynamic analysis system, cockpit system, and etc. In it is paper, the main procedures to develop the driving simulator are classified by five parts. First, a motion bed system and a motion controller, which can track a reference trajectory, are developed. Secondly, a performance evaluation of the motion bed system for the driving simulator is carried out using LVDTs and accelerometers. Thirdly, a washout algorithm to realize a motion of an actual vehicle in the driving simulator is developed. The algorithm changes the motion space of a vehicle into the workspace of the driving simulator. Fourthly, a visual and audio system for feeling higher realization is developed. Finally, an integration system to communicate and monitor between sub systems is developed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1252-1264
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• 1988

Recently industrial robots together with positioners are often used to enhance the system performance for arc welding. In this paper, a redundancy control method is proposed to the robot-positioner system with seven degrees of freedom, where one kinematic modelling technique is employed. Also, manipulability in the given cutting plane of the workspace. An algorithm maximizing the manipulability is applied to the robot and the positioner and the simulation results are shown for the task following a linear path.

• Advances in robotics research
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• v.1 no.1
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• pp.81-99
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• 2014

This paper contributes towards the development of a computer vision system for telemonitoring of industrial articulated robotic arms. The system aims to provide precision real time measurements of the joint angles by employing low cost cameras and visual markers on the body of the robot. To achieve this, a mathematical model that connects image features and joint angles was developed covering rotation of a single joint whose axis is parallel to the visual projection plane. The feature that is examined during image processing is the varying area of given circular target placed on the body of the robot, as registered by the camera during rotation of the arm. In order to distinguish between rotation directions four targets were used placed every $90^{\circ}$ and observed by two cameras at suitable angular distances. The results were deemed acceptable considering camera cost and lighting conditions of the workspace. A computational error analysis explored how deviations from the ideal camera positions affect the measurements and led to appropriate correction. The method is deemed to be extensible to multiple joint motion of a known kinematic chain.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.230-233
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• 2011

Chronic disease is linked to patient's' lifestyle. Therefore, doctor has to monitor his/her patient over time. This may involve reviewing many reports, finding any changes, and modifying several treatments. One solution to optimize the burden is using a visualizing tool over time such as a timeline-based visualization tool where all reports and medicine are integrated in a problem centric and time-based style to enable the doctor to predict and adjust the treatment plan. This solution was proposed by Bui et. al. [2] to observe the medical history of a patient. However, there was limitation of studying the diabetes patient's history to find out what was the cause of the current development in patient's condition; moreover what would be the prediction of current implication in one of the diabetes' related factors (such as fat, cholesterol, or potassium). In this paper, we propose a Grid-based Interactive Diabetes System (GIDS) to support bioinformatics analysis application for diabetes diseases. GIDS used an agglomerative clustering algorithm as clustering correlation algorithm as primary algorithm to focus medical researcher in the findings to predict the implication of the undertaken diabetes patient. The algorithm was Chronological Clustering proposed by P. Legendre [11] [12].

• Advances in nano research
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• v.15 no.3
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• pp.277-283
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• 2023

This research aims to explore factors influencing creativity among the employees of nanotechnology companies. Further, this survey aimed to investigate the role of psychological capital (PS), job satisfaction (JS) and corporate social responsibility (CSR) as sources to foster creativity. Participants included 375 employees of nanotechnology companies in China. Sequential mediation analysis revealed that creativity was significantly influenced by psychological capital, job satisfaction and corporate social responsibility. Furthermore, not only psychological capital, job satisfaction and corporate social responsibility were directly and indirectly related to creativity but also explained 67.35% variance of it. It seems that having more psychological resources, more well-being and good feelings concerning performance in the workspace and the efforts of companies to improve employee welfare are among the most important factors in increasing employee creativity. Our findings can help companies, especially nontechnology companies, in focusing on factors fostering the creativity of employees, because creativity enhances and promotes the performance and success of companies.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.146-153
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• 2014

This study looks at the impact of psychological and physical factors of the working conditions on the health of workers depending on whether technology is used by such workers. The data used for the study is the third work environment survey. Out of 50,032 respondents, a total of 29,711 paid workers were used as analysis subjects. Although it was anticipated that the use of technology was a factor that hindered job autonomy and teamwork autonomy. However, the analysis results showed low levels of job autonomy and teamwork autonomy in the group that did not use technology. The study assumes a regression analysis model about work environment and work organizational practices of workspaces that have an impact on musculoskeletal complaints, stress symptoms and level of work satisfaction by controlling the social demographic variable that represents the level of individual sensitivity. As a result of the study, ergonomic risk had a significant effect on both groups that did or did not use technology with respect to stress symptoms, musculoskeletal complaints and level of work satisfaction. In particular, as workspace practices and work environment had an effect on the development of musculoskeletal complaints in the group that used machines, there is a need to improve such situation. The autonomous team work or level of job autonomy within the group that used technology may act as a risk factor to the health and welfare of workers. However, because it may also act as a buffer factor, there is a need for a change to reduce stress symptoms and increase the level of work satisfaction by improving autonomous team work and the level of job autonomy.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.81-90
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• 2000

Parallel manipulator is suitable for the high precise task because it than has higher stiffness, larger load capacity and more excellent precision, due to the closed-lop structure, than serial manipulator. But the controller design for parallel manipulator is difficult because the parallel manipulator has both the complexity of structure and the interference of actuators. The precision improvement of parallel manipulator using a classical linear control scheme is difficult because the parallel manipulator has the tough nonlinear characteristics. In this paper, firstly, the kinematic analysis of a parallel manipulator used at the experiments is performed so as to show the controllability. The analysis of internal singular configuration of the workspace is performed using the kinematic isotropic index so a sto show the limitation of control performance of a simple linear controller with fixed control gains. Secondly, a control scheme is designed by using an adaptive fuzzy logic controller so that active joints of the parallel manipulator track more precisely the desired input trajectory. This adaptive fuzzy logic controller so that active joints of the parallel manipulator track more precisely the desired input trajectory. This adaptive fuzzy logic controller is often used for the control of nonlinear system because it has both the inference ability and the learning ability. Lastly, the effeciency of designed control scheme is demonstrated by the real-time control experiments with IBM PC interface logic H/W and S/W of my won making. The experimental results was a success.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.839-845
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• 2018

As a solution to the rural shortage of labor, mechanization crop production is necessary, but in some cases, the mechanization can cause problems such as a decrease in products due to the expansion of the necessary moderate workspace. The purpose of this study was to compare the yields of pepper by the planting-density for the mechanization of pepper cultivation. Experiments were done with three planting-density levels of $900{\times}300mm^2$(A-T), $1200{\times}450mm^2$(B-T), and $1500{\times}600mm^2$(C-T). In the analysis of growth, the highest values in plant height and thickness and the number of branches were observed with the B-T. C-T showed the highest values in the number of green-pepper and red-pepper and weight of the green-pepper and red-pepper, followed by B-T and A-T. In the analysis of growth, it was concluded that the proportion of the pepper body to the total length increased as the planting-density decreased. C-T had the biggest maximum diameter of the body, followed by B-T and A-T. On the other hand, A-T had the biggest minimum diameter of the body, followed by B-T and C-T. It was judged that the larger the planting-density was, the shorter the length was and the thicker the form was. As a result of measuring the chromaticity, there was no significant statistical difference in quality. Based on the experiment results, the ranking in total yields was in the order of C-T, B-T, and A-T. The reduced planting-density seemed to increase the productivity, while the labor intensity and time were reduced due to the improvement of the working environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2205-2212
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• 1996

In order to move the body of a walking robot translationally, and step over the obstacles, the walking robot must have at least 3 degrees of freedom for each leg. Therefore each leg of the general walking robots can be composed of 3-link system with 3 revolute joints. In this paper, the colsed form of inverse kinimatic solutions is shown for this general 3R linkage. Moreover, in order to have efficient walking volume in rough terrain, the workspace of each log is obtained considering the twist angles and the offsets in D-H parameters. When we design a walking robot, the information of the walking volume is needed for planning desired trajectories of the feet effectively. Appropriate knowledge of the walking volume can also be used to maximize linear or angular velocity of minimize power of stress. However, since it is impossible to obrain the information of walking volume in 3-D space directly from the kinematic equations, the walking volume can be searched through the edge detection algorithm using the triangle tracer with closed from inverse kinematic solutions. In this study, we present the closed form inverse kinematic solutions for 3R linkage model, and the walking volume of 6 legged walking robot which is modeled after the darking bettle, Eleodes obscura sulcipennis, through the method of edge detection for an arbitrary 2 dimensional shape using triangle tracer.